Re: CVE request - kernel: information leak in sigaltstack

[Eugene Teo <eugene () redhat com>]

Eugene Teo wrote:
> do_sigaltstack: avoid copying 'stack_t' as a structure to user space
>
> Ulrich Drepper correctly points out that there is generally padding in
> the structure on 64-bit hosts, and that copying the structure from
> kernel to user space can leak information from the kernel stack in those
> padding bytes.
>
> Avoid the whole issue by just copying the three members one by one
> instead, which also means that the function also can avoid the need for
> a stack frame. This also happens to match how we copy the new structure
> from user space, so it all even makes sense.
>
> Upstream commit:
> http://git.kernel.org/linus/0083fc2c50e6c5127c2802ad323adf8143ab7856
>
> Reference:
> https://bugzilla.redhat.com/show_bug.cgi?id=515392

Reproducer:
http://milw0rm.com/exploits/9352

Thanks, Eugene